/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.datayoo.moql.operand.function;

import org.datayoo.moql.EntityMap;
import org.datayoo.moql.Operand;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * 
 * @author Tang Tadin
 *
 */
public class Percentile extends AggregationFunction {
	
	public static final String FUNCTION_NAME = "percentile";

	protected org.apache.commons.math3.stat.descriptive.rank.Percentile percentile;
	
	protected Set<Double> numbers = new HashSet<Double>();
	
	public Percentile(List<Operand> parameters) {
		super(FUNCTION_NAME, parameters.size(), parameters);
		// TODO Auto-generated constructor stub
		if (parameters.size() == 0 || parameters.size() > 2) {
			throw new IllegalArgumentException("Invalid format! The format is 'percentile(field [, p])'");
		}
		if (parameters.size() == 1) {
			percentile = new org.apache.commons.math3.stat.descriptive.rank.Percentile();
		}
	}

	@Override
	public void increment(EntityMap entityMap) {
		// TODO Auto-generated method stub
		if (percentile == null) {
			Object obj = parameters.get(1).operate(entityMap);
			Number num = toNumber(obj);
			percentile = new org.apache.commons.math3.stat.descriptive.rank.Percentile(num.doubleValue());
		}
		Object obj = parameters.get(0).operate(entityMap);
		if (obj == null) {
			return;
		} 
		Number num = toNumber(obj);
		numbers.add(num.doubleValue());
	}

	@Override
	public Object getValue() {
		// TODO Auto-generated method stub
		double[] values = new double[numbers.size()];
		int i = 0;
		for(Double num : numbers) {
			values[i++] = num;
		}
		return percentile.evaluate(values);
	}

	@Override
	public void clear() {
		// TODO Auto-generated method stub
		numbers.clear();
	}

}
